The party’s need to maintain stable rule over an increasingly vocal military is one reason Mr. Hu, its top civilian leader, is expected to hold on to his position as chairman of the Central Military Commission for up to two years after he gives up his party chief title in the fall, according to people briefed on political discussions. His anointed successor, Xi Jinping, would still take over Mr. Hu’s posts as head of the party and head of state, but would have to wait to become China’s military boss.

Mr. Hu’s two predecessors both exercised control of the military after they gave up their other civilian titles. But some party insiders have argued that a staggered handover can lead to rival centers of power, splitting generals’ loyalties. No final decision has been made on whether Mr. Hu will stay on. But if he does, then Mr. Xi could find himself with limited room to expand his power base, even though he has more of a military background than Mr. Hu.

Mr. Hu has been building a network of army loyalists by promoting generals in waves. At least 45 officers have been promoted to full general by Mr. Hu since September 2004, when he became head of the military commission. Just over half the promotions have taken place since July 2010. Four of the 45 are now among the 10 generals who sit on the commission.